Brian Murphy 7333694830 Stats : Add time in index throttle to stats.
This commit adds throttle stats to the indexing stats and uses a call back from InternalEngine to manage the stats.
Also includes updates the IndexStatsTests to test for these new stats.
Stats added :
```
throttle_time_in_millis
is_throttled
```

Closes #7861
2014-10-22 14:07:28 +01:00
..